Objective lens for endoscopes
First Claim
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1. An objective lens for an endoscope which has an optical lens system including a plurality of optical lens elements arranged at predetermined axial distances, said objective lens system comprising:
- a lens barrel in which said optical lens elements are coaxially placed; and
an aperture ring disposed between an adjacent two of said lens elements for restricting light rays entering said optical system and positioning said adjacent two lens elements at a specified axial distance;
said aperture ring having an aperture having a marginal edge, said marginal edge being in contact with both of said adjacent two lens elements;
said aperture ring having a thickness less than approximately 0.1 mm.
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Abstract
An objective lens for an endoscope has an optical lens system including a plurality of optical lens elements coaxially arranged at predetermined axial distances, at least an adjacent two of which are spaced at a specified relative axial distance by a thin ring member for restricting light rays entering the optical system.
51 Citations
12 Claims
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1. An objective lens for an endoscope which has an optical lens system including a plurality of optical lens elements arranged at predetermined axial distances, said objective lens system comprising:
a lens barrel in which said optical lens elements are coaxially placed; and
an aperture ring disposed between an adjacent two of said lens elements for restricting light rays entering said optical system and positioning said adjacent two lens elements at a specified axial distance;
said aperture ring having an aperture having a marginal edge, said marginal edge being in contact with both of said adjacent two lens elements;
said aperture ring having a thickness less than approximately 0.1 mm.- View Dependent Claims (2, 3, 4, 5)
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6. An objective lens for an endoscope which has an optical lens system including from the object end to the image end first, second and third optical lens elements L1 -L3 coaxially arranged at axial distances in a lens barrel and an aperture stop ring member disposed between said second and third optical lens elements for restricting light rays entering said optical system and positioning said second and third optical lens elements at a specified axial distance, said third optical lens element L3a and L3b cemented together, and said optical lens system being substantially described as follows:
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space="preserve" listing-type="tabular"> TABLE II ______________________________________ Radius of Axial Distance Element Curvature (mm) Between Surfaces N.sub.d ν
.sub.d ______________________________________ r.sub.1 = ∞
L.sub.1 d.sub.1 = 0.40 1.88299 40.9 r.sub.2 = 0.7772 d.sub.2 = 0.23 r.sub.3 = 3.5183 L.sub.2 d.sub.3 = 1.75 1.80517 25.4 r.sub.4 = -1.4831 d.sub.4 = 0.02 r.sub.5 = ∞
L.sub.3a d.sub.5 = 0.40 1.80517 25.4 r.sub.6 = 1.9530 d.sub.6 = 0 r.sub.7 = 1.9530 L.sub.3b d.sub.7 = 1.18 1.69680 55.6 r.sub.8 = -1.7595 ______________________________________wherein the lens elements L1 -L3b have surface radii r1 -r8, the index of refraction is given by Nd, the dispersion is measured by the Abbe number as given by Vd, and the axial distance between adjacent surface is given by d in millimeters (mm). - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification